Known in the prior art are antianginal preparations used to arrest attacks of stenocardia containing active substances such as glyceryl trinitrate, isosorbide dinitrate, pentaerythritol tetranitrate, and others.
In addition to said active substances these medicinal preparations contain an inert carrier which is resolved in liquid media of the body. For example, used in the prior art are granules of glyceryl trinitrate containing sugar, starch, and other substances as filling materials (Soviet State Pharmacopoeia, 10th edition).
A disadvantage of the known medicinal preparations containing readily soluble substances, such as sugar, as a filling material, is their low stability in storage and lock of prolonged action.
Also known in the prior art are also tablets of glyceryl trinitrate, prepared by the microcapsulation method (Sustac, Nitrong) wherein the microcapsules perform the function of the carrier material, which is derivatives of cellulose, such methyl cellulose, ethyl cellulose, acetyl cellulose, cellulose acetophthalate, etc. (See U.S. Pat. No. 3,344,029).
Medicinal preparations enclosed in microcapsules start exerting their medicinal action at delayed (to 60 minutes) terms, and this makes it impossible to use them for rapid arresting of stenocardia attacks.
Another disadvantage of capsuled preparations is the relative complexity of their manufacture.
Known widely in the prior art are antianginal preparations manufactured in the form of tablets and dragee. These also include multi-coated pills, containing synthetic polymers, such as polyvinyl alcohol, and a copolymer of polyvinyl alcohol and vinyl acetate, as resolvable carrier material. Synthetic polymers are used to coat tablets or granules so that the rate of liberation of the active principle could be controlled. (French Pat. No. 2,326,933; U.S. Pat. No. 4,012,498).
Also known in the prior art are antianginal preparations in the form of chewing gum containing the active principle and various additives. The base material used in these preparations are polyacrylate polymers (U.S. Pat. No. 3,594,470).
The disadvantage of the known medicinal preparations in the form of tablets pressed with powdered synthetic polymers, and also enclosed in coats of such polymers, is that they can be improperly administered (especially by children who can chew them before swallowing) and hence produce undesirable side effects due to rapid uncontrolled absorption into the body.
The method of treating with such medicinal preparations involves the patient swallowing the medicine (peroral administration), or placing it under the tongue until it fully resolves (sublingual administration) or chewing the gum to ensure gradual administration of the medicine with saliva. In all these administration methods, the active principle penetrates the alimentary tract where it is dissolved, absorbed through the mucosa, and delivered first to the liver and then to the blood circulating system (Petkov, V., "Medicine, Body, Pharmacological Effect", Medicina i Fizkultura, Sofia, 1974).
The general pharmacological disadvantage inherent in all known medicinal antianginal preparations and methods of manufacturing thereof is that when the preparations enter the alimentary tract, and later the liver, the liberated active substance is partially inactivated by the enzymatic systems in the body. The degree of inactivation of the preparations depends on specific characteristics of the living body and its physiological state, which, in general, makes it impossible to dose the medicinal preparation individually so as to ensure its optimum effect.
The main object of this invention is to provide a novel medicinal form, viz., a medicinal film having antianginal action, characterized by prolonged action, improved accuracy of dosage of the active substance, and stability in storage.
The specific object of the invention is to provide a novel medicinal form, namely, antianginal film, which can be used as a medicinal preparation characterized by prolonged action, increased accuracy of dosage of the active principle, and stability in storage.